Potential problems following cavity wall insulation

Cavity wall insulation can cause damp, but it’s worth assessing whether your home is at risk by using the checklist below. Also ask any potential installer about these factors before committing to the work.

Damp could occur in properties as a result of cavity wall insulation if there is a combination of these factors:

• Your home is exposed to severe levels of wind-driven rain.
• Your home is located in an unsheltered position, e.g. not protected by trees or other buildings.
• The external walls are poorly built or maintained with, for example, cracks in the brickwork or rendering.

Published guidance by the Building Research Establishment says that in these cases there is ‘an increased risk of rain penetration if a cavity is fully filled with insulation’. Rain could penetrate the outer wall, bridge the cavity via the insulation material and transfer moisture to internal walls, causing damp.

Areas of the UK exposed to wind and rain

Damp in exterior wall as a result of cavity wall insulation.